JPH0333891B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a Fe-TiC sintered material that has excellent wear resistance and extremely low attack resistance, and is particularly suitable for use as a sliding member of internal combustion engines whose operating conditions are becoming increasingly severe. It is something. Conventionally, various materials have been used to manufacture sliding members such as parts, cams, valve guides, and sleeves used for rocker arm sliding surfaces of internal combustion engines. However, in recent years, exhaust gas regulations have been compulsorily enforced for internal combustion engines, such as diesel engines, from the standpoint of environmental protection.
Because the EGR (exhaust gas recirculation) mechanism is installed, not only does the lubricating oil deteriorate rapidly,
Degradation products, soot, and even moisture are generated and mixed into lubricating oil, and when exposed to such lubricating oil, sliding members made of conventional materials suffer from severe wear and attack by opponents. It was also expected to increase further. Therefore, from the above-mentioned viewpoint, the present inventors conducted research in order to obtain a material that has excellent wear resistance and is less likely to attack others. %, C: 5~20%, P: 0.1~
20%, Ti: 20-55%, and optionally one or two of Mo, Nb, W, V, and Zr: 0.2-5%, Ni, Co, Cu, and
Contains one or more of Mn: 0.5 to 5%, or both, with the remainder consisting of Fe and unavoidable impurities, and a matrix consisting mainly of martensite, mainly titanium carbide and chromium carbide. Fe-TiC-based sintered materials, which have a microstructure in which a hard phase consisting of They found that when used as a sliding member in an internal combustion engine that requires the following characteristics, it exhibits excellent performance over a long period of time. This invention was made based on the above knowledge, and the reason why the component composition was limited as described above will be explained below. (a) Cr The Cr component not only dissolves in the base material and strengthens it, but also combines with the C component to increase Bitkers hardness:
Forms chromium carbide with a carbon content of 1200 or more, which has the effect of improving the wear resistance of the material, but if the content is less than 1%, the desired wear resistance cannot be secured; The content was set at 1 to 15% because if the content exceeds that amount, the aggressiveness of the opponent will increase rapidly. (b) C The C component includes Cr and Ti (Ti is usually used as a raw material powder in the form of titanium carbide), as well as Cr and Ti (Ti is usually used as a raw material powder in the form of titanium carbide), as well as solid solution in the base material to strengthen it.
It combines with Mo, Nb, W, V, and Zr to form a hard carbide, which has the effect of improving the wear resistance of the material, but if its content is less than 5%, the desired effect is not achieved. On the other hand, if the content exceeds 20%, the material becomes extremely brittle, so the content was set at 5 to 20%. (c) P The P component generates a liquid phase during sintering to improve sinterability and densify the material.
It dissolves in solid solution in the base material and has the effect of improving conformability, but if the content is less than 0.1%, the desired effect will not be obtained, while if the content exceeds 2%, the material will become brittle. Because it becomes noticeable,
Its content was set at 0.1-2%. (d) Ti The Ti component mainly exists in the form of titanium carbide (hereinafter referred to as TiC) in the matrix and forms a hard phase, but this TiC has a density of 4.9 g/cm ³ (relatively low density). , Bitkers hardness: approx. 3200, melting point:
Because it has a property of 3250℃, the material not only has excellent wear resistance due to its own high hardness, but also has the effect of reducing adhesion with mating parts. However, the TiC content is
If the Ti content is less than 20% (TiC content less than 25%), the desired effect cannot be obtained, while if the Ti content exceeds 55% (TiC content 70%), the material becomes brittle. TiC
The content was determined to be 20 to 55% in terms of Ti amount. (e) Mo, Nb, W, V, and Zr These components not only solidly dissolve in the base material and strengthen it, but also combine with the C component to form hard carbides, which improve the wear resistance of the material. Since it has the effect of further improving wear resistance, it is included as necessary especially when even higher wear resistance is required, but if the content is less than 0.2%, the desired wear resistance improvement effect cannot be obtained. On the other hand, if the content exceeds 5%, the aggressiveness of the opponent increases rapidly, so the content was set at 0.2 to 5%. (f) Ni, Co, Cu, and Mn These components dissolve in solid solution in the base material and have the effect of further improving the toughness of the material, so they may be included as necessary when particularly toughness is required. However, if the content is less than 0.5%, the desired effect of improving toughness cannot be obtained, and on the other hand, even if the content exceeds 5%, no further effect of improving toughness will be obtained. %. In addition, in the material of this invention, if the density ratio of the material is less than 90%, the strength of the base will be low and large pores will be present, and the base will be destroyed due to the notch effect of these pores. 90% of the
It is desirable to have a density ratio of 30% or higher, and if the ratio of the hard phase is less than 30% in terms of area ratio, it is not possible to secure the desired excellent wear resistance. It is desirable that there be at least one. Furthermore, in order to ensure the desired wear resistance, the base martensite preferably occupies 60% or more in terms of area ratio. Next, the sintered material of the present invention will be specifically explained with reference to Examples. Example Atomization of particle size -100mesh as raw material powder
Fe-Cr alloy (Cr: 12.5% content) powder,
100mesh high carbon Fe-Cr alloy (Cr: 60% content)
Powder, -250mesh TiC (C: 20% content) powder,
-350mesh Fe-P alloy (P: 17% content) powder, -250mesh Fe-P alloy (P: 25.7% content) powder, flaky graphite powder, particle size -350mesh
Mo powder, -200mesh Fe-Nb alloy (Nb: 15% content) powder, -200mesh Fe-V alloy (V: 70% content) powder, W powder with average particle size: 10μm,
Ni powder, Co powder, Cu powder with particle size -200mesh, Fe-Zr alloy (contains Zr: 60%) with particle size -200mesh
Powder, same 200mesh Fe-Mn alloy (Mn: 78%
(containing) powder is prepared, and each of these raw material powders is shown in Table 1.

【table】

【table】

【table】

【table】

[Table] After adding 0.5% zinc stearate as a lubricant and mixing with a V-type mixer,
It is formed into a green compact at a pressure of 5 ton/cm ² , and then the green compact is heated to a temperature of 1000 to
Sintered by holding at a predetermined temperature within the temperature range of 1250℃ for 60 minutes, and in case of vacuum sintering, after sintering, temperature: 1000℃
Harden by forced air cooling from ℃, or in the case of sintering in a reducing atmosphere, after sintering in a carburizing atmosphere,
By performing oil quenching upon cooling to a temperature of Comparative Sintered Materials 1-29 and Comparative Sintered Materials 1-6 were produced, respectively. In addition, comparative sintered materials 1 to 6 all have compositions in which the content of one of the constituent components (those marked with * in Table 1) is outside the scope of this invention. . Next, the resulting sintered materials of the present invention 1-
29 and Comparative Sintered Materials 1 to 6, a chip material suitable for the part surface of a rocker arm of an automobile engine was manufactured, this chip material was cast in when casting a rocker arm, and this Al alloy rocker arm was assembled into a 4-cylinder OHC engine. , oil used:
A wear resistance test was conducted under the conditions of SAE10W degraded oil, rotation speed: 850 r.pm, and operating time: 200 hours. 0.7%,
The wear amount of a cam made of cast iron containing Cr: 0.8% and P: 0.2% was measured. These results are shown in Table 2.
Table 2 also shows the results when the chip material was a chill casting of cast iron having the above composition. From the results shown in Table 2, the sintered material 1 of the present invention
-29 all have superior wear resistance and are significantly less aggressive than conventional chilled castings, whereas as seen in comparative sintered materials 1 to 6. It is clear that if the content of any one of the constituent components deviates from the range of the present invention, at least one of the above-mentioned properties will become inferior. As mentioned above, the Fe-TiC-based sintered material of the present invention has excellent wear resistance and is extremely less aggressive to others, so it is inevitable that it will be used under particularly harsh conditions. When used as a sliding member in modern internal combustion engines, it stably exhibits excellent performance over a long period of time.

Claims (1)

[Claims] 1 Cr: 1 to 15%, C: 5 to 20%, P: 0.1 to 2%, Ti: 20 to 55%, and the remainder is Fe and unavoidable impurities. % by weight), and a structure in which a hard phase mainly consisting of titanium carbide and chromium carbide is finely and uniformly dispersed in a matrix mainly consisting of martensite.
Fe-TiC sintered material. 2 Cr: 1 to 15%, C: 5 to 20%, P: 0.1 to 2%, Ti: 20 to 55%, and further contains one of Mo, Nb, W, V, and Zr. Or two or more types: 0.2 to 5%, with the remainder consisting of Fe and unavoidable impurities (wt%), and a matrix consisting mainly of martensite with a fine hard phase mainly consisting of titanium carbide and chromium carbide. An Fe-TiC-based sintered material for sliding members of internal combustion engines, characterized by containing a uniformly dispersed structure. 3 Contains Cr: 1 to 15%, C: 5 to 20%, P: 0.1 to 2%, Ti: 20 to 55%, and further contains one or two of Ni, Co, Cu, and Mn. Species or higher: Contains 0.5 to 5%, with the remainder consisting of Fe and unavoidable impurities (weight%), and a hard phase consisting mainly of titanium carbide and chromium carbide is finely and uniformly formed on a matrix mainly consisting of martensite. For sliding members of internal combustion engines, characterized by having a dispersed structure.
Fe-TiC sintered material. 4 Cr: 1 to 15%, C: 5 to 20%, P: 0.1 to 2%, Ti: 20 to 55%, and further contains one of Mo, Nb, W, V, and Zr. or two or more types: 0.2 to 5%, and one or more types of Ni, Co, Cu, and Mn: 0.5 to 5%, with the remainder consisting of Fe and unavoidable impurities (by weight %), and a structure in which a hard phase mainly consisting of titanium carbide and chromium carbide is finely and uniformly dispersed in a matrix mainly consisting of martensite.
Fe-TiC sintered material.